PB vs BZ

There are two fundamental differences between bromide and Benzotriazole:

1. Bromide is typically not used up during development, whereas Benzotriazole (and most other organic restrainers) ia. This matters mostly if developers are reused.
2. If concentration of bromide rises above a rather high level, it actually acts as silver solvent due to higher silver bromide complex formation. Benzotriazole does not do this AFAIK. This matters if you need lots of restrainer to tackle heavily fogged paper.

I would not consider image tone a strong argument for or against bromide or Benzotriazole, since modern papers barely change their tones with either one.

Rudeofus said:

There are two fundamental differences between bromide and Benzotriazole:

1. Bromide is typically not used up during development, whereas Benzotriazole (and most other organic restrainers) ia. This matters mostly if developers are reused.
2. If concentration of bromide rises above a rather high level, it actually acts as silver solvent due to higher silver bromide complex formation. Benzotriazole does not do this AFAIK. This matters if you need lots of restrainer to tackle heavily fogged paper.

I would not consider image tone a strong argument for or against bromide or Benzotriazole, since modern papers barely change their tones with either one.

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Thank you for the clarification.

Donald Qualls said:

Potassium bromide, in my experience, makes a much better "integrated" restrainer -- that is, written into the developer formula, mixed along with the developing agent(s), preservative, accelerator, grain modifiers. Benzotriazole is almost never called out to go in the original developer mix, probably because it's so much more effective. Too effective.

Sure, for shooting forty-fifty year old film, BZ does the job much better than KBr -- but that is (or ought to be) an unusual situation. Most developers are designed for the situation of most photographers -- shooting fresh (or at least recently expired) film and processing it more or less promptly.

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Hello, I have been out of the darkroom for about 15yrs, so getting back into it I realized that I have a lot of exposed, undeveloped film. Developing this film, in your opinion, should I increase dev time say abt 20%? I use mostly Ilford HP4 & HP5 (35mm & 4x5). Thanks for your input, Paul

PDL45 said:

Hello, I have been out of the darkroom for about 15yrs, so getting back into it I realized that I have a lot of exposed, undeveloped film. Developing this film, in your opinion, should I increase dev time say abt 20%? I use mostly Ilford HP4 & HP5 (35mm & 4x5). Thanks for your input, Paul

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Are you following me? I just got my darkroom back in operation a few months ago after more than ten years without one. In my experience, you don't need to adjust developing times at all for film exposed as recently as fifteen years ago. The main exception, among reasonably modern films, seems to be Pan F, which has serious issues with latent image fading -- but adjusting development won't really help that much; you just need to develop that film within, ideally, days of exposure, or weeks at least. Over a course of mere months image quality will suffer.

For most other films (in my recent experience, Fuji Superia X-Tra 400, Fomapan 100 and 400, and Ferrania 400 color) ten years of room temperature storage after exposure has little effect -- none that can be improved by adjusting development time.

Donald Qualls said:

Are you following me? I just got my darkroom back in operation a few months ago after more than ten years without one. In my experience, you don't need to adjust developing times at all for film exposed as recently as fifteen years ago. The main exception, among reasonably modern films, seems to be Pan F, which has serious issues with latent image fading -- but adjusting development won't really help that much; you just need to develop that film within, ideally, days of exposure, or weeks at least. Over a course of mere months image quality will suffer.

For most other films (in my recent experience, Fuji Superia X-Tra 400, Fomapan 100 and 400, and Ferrania 400 color) ten years of room temperature storage after exposure has little effect -- none that can be improved by adjusting development time.

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I hope you're right. I have some undeveloped roll film and sheet film that should have been developed something like 10 or 12 years ago. In some cases they are duplicate shots of some copy work and it will be interesting to compare my results with the identically exposed films already developed. It would be good to have backup copies of some 19th century photos, the most precious of which was destroyed by my grumpy old uncle before he died.

Thanks I'll read it later

john_s said:

I hope you're right. I have some undeveloped roll film and sheet film that should have been developed something like 10 or 12 years ago. In some cases they are duplicate shots of some copy work and it will be interesting to compare my results with the identically exposed films already developed. It would be good to have backup copies of some 19th century photos, the most precious of which was destroyed by my grumpy old uncle before he died.

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I've seen problems with mottling in sheet film (1990s vintage 320TXP and mid-oughties Fortepan 400) that sat in film holders for twelve years or so, but I think that's humidity related -- condensation can move dyes around in the emulsion and result in local changes in sensitivity, potentially also chemical fogging -- but sensitizing dye movements won't affect a latent image, they just locally change film speed and/or spectral response (evidence for this: unexposed .EDU Ultra = Fomapan in 120 that was stored out of its wrapper in a 120 film can over that time had mottling, but exposed film stored the same way, same location, was fine. I haven't yet reloaded any of those film holders -- but again, the film itself was stored the same way, in unsealed original packaging (black bag inside the box), so there's a possibility of humidity damage. I haven't yet gotten around to processing the backup copies I've had curled up inside a homemade processing tank -- tried to take them out of that tank to process in my Yankee Agitank, but they were so curly I couldn't get them to load in the Yankee film carrier. Sometime soon I'll go ahead and process them, if only to get the loaded tube tank off my darkroom counter.

Bottom line, in general, film already exposed may be subject to latent image fading (though the newer the film, the less of that you'll see and for most films a decade isn't long enough to matter much), but is less affected by storage conditions. Unexposed film, if not sealed, may be subject to humidity-related damage; unexposed film in original airtight packaging is likely to be fine over that sort of time frame.